Refinement of nickel alloys



Patented Apr. 30, 1929. p

, 1,710,846 UNITED STATES PATENT. OFFICE.

WILLOUGHBY sm'raan sm'rn, or remnants, HENRY Josnrn GARRETT, or

LYNNE, AND JOHN ANGEL HOLDEN, 0F SUNNYSIDE, ENGLAND.

anrmmnnr or NICKEL ALLpYs.

No Drawing. Application filed May 3, 1928, Serial No. 274,959, and iiiGreat Britaip April 25, 1927.

difficult to work' when they contain even a small percentage ofsulphur;'amounts of as little as 03% in certain alloys are veryinjurious.

If pure virgin metals are melted into alloys in furnaces in which thereisno contamination and the alloys are subsequently worked by ordinarycommercial processes, contamination by sulphur is almost inevitable.Such operations as preheating for rolling or for forgingiin gas or coalfired furnaces lead to an absorption of sulphur, which is necessarilyconfined to the surface of the material. When the rolled or forged scrapis returned to the furnace for melting, a small increment of sulphur ismade to the charge. During the course of time thisinorement becomesgreater, till eventually the material contains so much impurity that itcannot be worked as perfectl'y as the pure alloy.

According to this invention the charge consisting for example, of virginmetal with scrap or entirely of scrap is melted in the presence of aslag-and hydrogen or other reducing atmosphere. A suitable slag consistsmainly of lime with silica, and a small amount of either fluo'rspar orcalcium chloride may be used. Preferably the furnace is of the,induction type, using low, medium or high frequency.

It has been found that fifteen minutes refining with a slag of thecomposition mentioned, in an atmosphere as described, will reduce thesulphur content'very considerably in an alloy containing of nickel. Thehydrogen supply is then cut off and the slag removed from the surface ofthe metal, and

our invention We have slgned our-names this before a new slag is formed,a small amount 7 of an oxide of one of the constituents of the oxide ofironFe O or Fe O, -may be infurnace few minutes and then a new slag isformed from suitable materials, etc. ing.

It is possible however after removal of the hydrogen directly to teemthe metal from such as broken glass, The molten metal is then ready. forpourthe crucible but if so it will be found that during freezing a largevolume of hydrogenis evolved and in consequence the resulting ingots arehoneycombed. 7 Even with the use of de-gasifying agents, such asmanganese, magnesium, silicon and the like, the resulting bars areworthless. They can, nowevor, be remelted in .the ordinary way and madeinto sound workable ingots (becausethe hydrogen is expelled duringfreezing), but this is not so economical as the method described above.

Additions of a suitable finishing agent such asmagnesium are made in theusual manner.

Whatwe claim is i 1. A method for the refinement by minimizing thesulphur content of nickel alloys having a nickel content of 50% or more,which consists in melting the furnace charge in the presence of a slagand an atmosphere of hydrogen, and subsequently after removal of thereducing atmosphere adding an oxide of one of theconstituent metals toabsorb the absorbed hydrogen. 2. 'A method for the refinement byminimizing the sulphur content of nickel alloys having a nickel contentof 50% or more, which consists in melting the furnace charge in thepresence of a slag and hydrogen, cutting off the supply of hydrogenafter about fifteen minutes and. then adding a small amount of an oxideof one of the constituents of the alloy for removing the absorbedhydroen. b In testimony that we claim the foregoing as 18th 'day ofApril, 1928. WILLOUGHBY STATHAM SMITH. HENRY JOSEPH GARNETT. JOHN ANGELHOLDEN.-

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